Use of pulmonary capillary wedge pressure to assess severity of mitral stenosis: Is true left atrial pressure needed in this condition?

There is disagreement concerning the use of the pulmonary capillary wedge pressure (in place of left atrial pressure) in assessing the presence and severity of mitral valve disease. This study was done to assess the accuracy and reliability of an oximetrically confirmed pulmonary capillary wedge pressure in measuring the transvalvular pressure gradient and valve area in patients with mitral stenosis. In 10 patients with mitral stenosis (1 man and 9 women; mean age ± SD 47 ± 7 years), pulmonary capillary wedge pressure was measured through an 8F Goodale-Lubin catheter with its wedge position confirmed by oximetry (oxygen saturation ≥95%). In addition, a transseptal left atrial pressure was measured through a Brockenbrough catheter and left ventricular pressure was measured through a pigtail catheter. The mean and phasic left atrial and pulmonary capillary wedge pressures were similar (mean left atrial pressure 18 ± 6 mm Hg; mean pulmonary capillary wedge pressure 18 ± 8 mm Hg; p = NS). When the pulmonary capillary wedge pressure was used without adjustment for time delay, the transvalvular pressure gradient (9.8 ± 3.3 mm Hg) and valve area (1.5 ± 0.5 cm²) were significantly different (p <0.05) from the values obtained with use of left atrial pressure (7.2 ± 2.9 mm Hg and 1.7 ± 0.6 cm², respectively). In contrast, when the pulmonary capillary wedge pressure was adjusted for the time delay through the pulmonary vasculature, the difference in gradients averaged only 1.7 mm Hg and the mitral valve areas were similar. Thus, in patients with mitral stenosis, a properly obtained, confirmed and time-adjusted pulmonary capillary wedge pressure accurately reflects left atrial pressure. As a result, transseptal left heart catheterization (to measure left atrial pressure) is not necessary in these patients.